Advanced System Management in TiDB [TiDB v5]: Questions on IndexLookup Without Table Scan Described in the Lesson "Understanding Execution Plans"

This topic has been translated from a Chinese forum by GPT and might contain errors.

Original topic: TiDB 高级系统管理 [TiDB v5] :《理解执行计划》一课中,描述IndexLookup无需回表扫的疑问

| username: OnTheRoad

In the course TiDB Advanced System Management [TiDB v5] Module5-Lesson15-“Understanding Execution Plans” at 46 minutes and 08 seconds, there is an error in the video explanation. The video describes IndexLookup index read as not requiring a table lookup. However, according to the course material, as shown in the figure, isn’t it first IndexRangeScan_7 (Build) scanning the index to get RowID, and then executing TableRowIDScan (Probe) operator to fetch data from the table?